GEM HV Scan Runplan

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Draft HV Scan Runplan

  • Setup
    • Ensure sieve is out for left arm
    • Move target to thin Carbon Target
    • Set Left HRS magnets to fill the focal plane: Turn off p0 regulation to the quads, cycle Q2/Q3 if going to higher momentum and set to the following currents:
I (A)
Q1 800
Q2 458
Q3 423
    • HV for upper scintillator is on
      • Left arm - LeCroy HV GUI, Card 2, Channel 10 (-1400V)
      • Right arm - telnet hatsv3 port 2005, Card 9, Channel 6 (-1400V)
    • Prescale all triggers away except for T5
    • Ask for 200nA of beam
    • Adjust beam current such that T5 rate is ~200kHz
    • VDCs are ON
    • GEM HV On to low HV value (given below)


  • Scan
    • Scan the HV settings for the chamber as given in the table below
    • Take 200k events at each step
Chamber Low HV High HV Step size
UVA 3400 3800 40
INFN 3600 4200 60



  • Backout
    • VDCs Off
    • Trigger Scintillator off
    • GEM HV Off
    • Set LHRS back to PREX tune B: cycle quads if going to higher current, turn p0 regulation for 3 quads back on
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